6
6.0

Sep 23, 2013
09/13

by
Hui Li

######
6

######
0

######
0

Let $(M, \omega)$ be a connected, compact 6-dimensional symplectic manifold equipped with a semi-free Hamiltonian $S^1$ action such that the fixed point set consists of isolated points or surfaces. Assume dim $H^2(M)

Source: http://arxiv.org/abs/math/0312085v1

14
14

Sep 21, 2013
09/13

by
Hui Li

######
14

######
0

######
0

Let $(M, \omega)$ be a connected, compact symplectic manifold equipped with a Hamiltonian $S^1$ action. We prove that, as fundamental groups of topological spaces, $\pi_1(M)=\pi_1(\hbox{minimum})=\pi_1(\hbox{maximum})=\pi_1(M_{red})$, where $M_{red}$ is the symplectic quotient at any value in the image of the moment map $\phi$.

Source: http://arxiv.org/abs/math/0203075v2

21
21

Jul 20, 2013
07/13

by
Hui Li

######
21

######
0

######
0

We suggest a new approach that could be used for modeling both the large scale behavior of astrophysical jets and the magnetically dominated explosions in astrophysics. We describe a method for modeling the injection of magnetic fields and their subsequent evolution in a regime where the free energy is magnetically dominated. The injected magnetic fields, along with their associated currents, have both poloidal and toroidal components, and they are not force free. The dynamic expansion driven...

Source: http://arxiv.org/abs/astro-ph/0604469v1

5
5.0

Sep 21, 2013
09/13

by
Hui Li

######
5

######
0

######
0

Let $M$ be a connected compact quantizable K\"ahler manifold equipped with a Hamiltonian action of a connected compact Lie group $G$. Let $M//G=\phi^{-1}(0)/G=M_0$ be the symplectic quotient at value 0 of the moment map $\phi$. The space $M_0$ may in general not be smooth. It is known that, as vector spaces, there is a natural isomorphism between the quantum Hilbert space over $M_0$ and the $G$-invariant subspace of the quantum Hilbert space over $M$. In this paper, without any regularity...

Source: http://arxiv.org/abs/0706.1471v3

8
8.0

Sep 19, 2013
09/13

by
Hui Li

######
8

######
0

######
0

Let $G$ be a connected compact Lie group, and let $M$ be a connected Hamiltonian $G$-manifold with equivariant moment map $\phi$. We prove that if there is a simply connected orbit $G\cdot x$, then $\pi_1(M)\cong\pi_1(M/G)$; if additionally $\phi$ is proper, then $\pi_1(M)\cong\pi_1(\phi^{-1}(G\cdot a))$, where $a=\phi(x)$. We also prove that if a maximal torus of $G$ has a fixed point $x$, then $\pi_1(M)\cong\pi_1(M/K)$, where $K$ is any connected subgroup of $G$; if additionally $\phi$ is...

Source: http://arxiv.org/abs/0909.3179v3

6
6.0

Sep 18, 2013
09/13

by
Hui Li

######
6

######
0

######
0

Assume $(M, \omega)$ is a connected, compact 6 dimensional symplectic manifold equipped with a semi-free Hamiltonian circle action, such that the fixed point set consists of isolated points or compact orientable surfaces. We restrict attention to the case $\dim$ $H^2(M)

Source: http://arxiv.org/abs/math/0210431v1

15
15

Sep 18, 2013
09/13

by
Hui Li

######
15

######
0

######
0

Let the circle act holomorphically on a compact K\"ahler manifold $M$ of complex dimension $n$ with moment map $\phi\colon M\to\R$. Assume the critical set of $\phi$ consists of 3 connected components, the extrema being isolated points. We show that $M$ is equivariantly biholomorphic to $\CP^n$, where $n\geq 2$, or to $\Tilde G_2(\R^{n+2})$, the Grassmannian of oriented 2-planes in $\R^{n+2}$, where $n\geq 3$, with a standard circle action; we also show that $M$ is equivariantly...

Source: http://arxiv.org/abs/1211.0920v3

6
6.0

Sep 18, 2013
09/13

by
Hui Li

######
6

######
0

######
0

Let $(M, \omega)$ be a connected, compact symplectic manifold equipped with a Hamiltonian $G$ action, where $G$ is a connected compact Lie group. Let $\phi$ be the moment map. In \cite{L}, we proved the following result for $G=S^1$ action: as fundamental groups of topological spaces, $\pi_1(M)=\pi_1(M_{red})$, where $M_{red}$ is the symplectic quotient at any value of the moment map $\phi$. In this paper, we generalize this result to other connected compact Lie group $G$ actions. We also prove...

Source: http://arxiv.org/abs/math/0605133v3

3
3.0

Sep 17, 2013
09/13

by
Yi Zhang; Hui Li

######
3

######
0

######
0

In this paper, we propose a general form of the equation of state (EoS) which is the function of the fractional dark energy density $\Omega_{d}$. At least, five related models, the cosmological constant model, the holographic dark energy model, the agegraphic dark energy model, the modified holographic dark energy model and the Ricci scalar holographic dark energy model are included in this form. Furthermore, if we consider proper interactions, the interactive variants of those models can be...

Source: http://arxiv.org/abs/1003.2788v2

7
7.0

Sep 21, 2013
09/13

by
Hui Li; Yang Chen

######
7

######
0

######
0

Recent observations reveal that spectral breaks at ~GeV are commonly present in Galactic gamma-ray supernova remnants (SNRs) interacting with molecular clouds and that most of them have a spectral ($E^2dF/dE$) "platform" extended from the break to lower energies. In paper I (Li & Chen 2010), we developed an accumulative diffusion model by considering an accumulation of the diffusive protons escaping from the shock front throughout the history of the SNR expansion. In this paper,...

Source: http://arxiv.org/abs/1108.4541v3

7
7.0

Sep 21, 2013
09/13

by
Hui Li; Susan Tolman

######
7

######
0

######
0

Consider an effective Hamiltonian circle action on a compact symplectic $2n$-dimensional manifold $(M, \omega)$. Assume that the fixed set $M^{S^1}$ is {\em minimal}, in two senses: it has exactly two components, $X$ and $Y$, and $\dim(X) + \dim(Y) = \dim(M) - 2$. We prove that the integral cohomology ring and Chern classes of $M$ are isomorphic to either those of $\CP^n$ or (if $n \neq 1$ is odd) to those of $\Gt_2(\R^{n+2})$, the Grassmannian of oriented two-planes in $\R^{n+2}$. In...

Source: http://arxiv.org/abs/0905.4049v3

14
14

Sep 18, 2013
09/13

by
Marta Lewicka; Hui Li

######
14

######
0

######
0

We prove convergence of critical points $u^h$ of the nonlinear elastic energies $E^h$ of thin incompressible plates $\Omega^h=\Omega \times (-h/2, h/2)$, which satisfy the von K\'arm\'an scaling: $E^h(u^h)\leq Ch^4$, to critical points of the appropriate limiting (incompressible von K\'arm\'an) functional.

Source: http://arxiv.org/abs/1211.3942v1

12
12

Sep 22, 2013
09/13

by
Hui Li; Jiangfeng Du

######
12

######
0

######
0

The purity of a reduced state for spins that is pure in the rest frame will most likely appear to degrade because spin and momentum become mixed when viewed by a moving observer. We show that such a boost-induced decrease in spin purity observed in a moving reference frame is intrinsically related to the spatial localization properties of the wave package observed in the rest frame. Furthermore, we prove that, for any localized pure state with separable spin and momentum in the rest frame, its...

Source: http://arxiv.org/abs/quant-ph/0309144v2

15
15

Sep 21, 2013
09/13

by
Hui Li; Dimitri Kusnezov

######
15

######
0

######
0

The group theoretical treatment of bound and scattering state problems is extended to include band structure. We show that one can realize Hamiltonians with periodic potentials as dynamical symmetries, where representation theory provides analytic solutions, or which can be treated with more general spectrum generating algebraic methods. We find dynamical symmetries for which we derive the transfer matrices and dispersion relations. Both compact and non-compact groups are found to play a role.

Source: http://arxiv.org/abs/cond-mat/9907202v1

8
8.0

Sep 19, 2013
09/13

by
Hui Li; Dimitri Kusnezov

######
8

######
0

######
0

We show that dynamical symmetry methods can be applied to Hamiltonians with periodic potentials. We construct dynamical symmetry Hamiltonians for the Scarf potential and its extensions using representations of su(1,1) and so(2,2). Energy bands and gaps are readily understood in terms of representation theory. We compute the transfer matrices and dispersion relations for these systems, and find that the complementary series plays a central role as well as non-unitary representations.

Source: http://arxiv.org/abs/solv-int/9912007v1

4
4.0

Sep 22, 2013
09/13

by
Cong Yu; Hui Li

######
4

######
0

######
0

We investigate the global nonaxisymmetric Rossby vortex instability in a differentially rotating, compressible magnetized accretion disk with radial density structures. Equilibrium magnetic fields are assumed to have only the toroidal component. Using linear theory analysis, we show that the density structure can be unstable to nonaxisymmetric modes. We find that, for the magnetic field profiles we have studied, magnetic fields always provide a stabilizing effect to the unstable Rossby vortex...

Source: http://arxiv.org/abs/0906.5318v1

11
11

Sep 19, 2013
09/13

by
Hui Li; Yang Chen

######
11

######
0

######
0

W28 is one of the archetype supernova remnants (SNRs) interacting with molecular clouds. H.E.S.S. observation found four TeV sources which are coincident with the molecular clouds (MCs) around W28, but Fermi LAT detected no prominent GeV counterparts for two of them. An accumulative diffusion model is established in this Letter and the energetic protons colliding the nearby MCs are considered to be an accumulation of the diffusive protons escaping from the shock front throughout the history of...

Source: http://arxiv.org/abs/1009.0894v1

42
42

Jul 20, 2013
07/13

by
Hui Li; Yi Zhang

######
42

######
0

######
0

Applying Clausius relation with energy-supply defined by the unified first law of thermodynamics formalism to the apparent horizon of a massive cosmological model proposed lately, the corrected entropic formula of the apparent horizon is obtained with the help of the modified Friedmann equations. This entropy-area relation, together with the identified internal energy, verifies the first law of thermodynamics for the apparent horizon with a volume change term for consistency. On the other hand,...

Source: http://arxiv.org/abs/1304.4780v2

299
299

Aug 15, 2008
08/08

by
Hui Li, Yen-Tsung

######
299

######
0

######
0

Book digitized by Google from the library of Oxford University and uploaded to the Internet Archive by user tpb.

Source: http://books.google.com/books?id=kTkBAAAAQAAJ&oe=UTF-8

48
48

Jul 20, 2013
07/13

by
Robert C. Duncan; Hui Li

######
48

######
0

######
0

We consider a model for gamma-ray bursts (GRBs) from high-velocity neutron stars in the galactic halo. In this model, bursters are born in the galactic disk with large recoil velocities V_r, and GRBs are beamed to within emission cones of half-angle \phi centered on V_r. We describe scenarios for magnetically -channeled GRBs that have such beaming characteristics. We then make detailed comparisons of this halo beaming model (HBM) to BATSE and PVO data for GRB intensity & angular position...

Source: http://arxiv.org/abs/astro-ph/9702182v1

16
16

Sep 23, 2013
09/13

by
Hui Li; Edward E. Fenimore

######
16

######
0

######
0

We propose a new, simple but powerful algorithm to analyze the gamma-ray burst temporal structures based on identifying non-statistical variations (``peaks'') in the time histories. Detailed analyses of the bursts from the third BATSE catalog show that $\sim 30$ bursts have more than 20 peaks individually. Upon identifying most of the peaks in those bursts, we show that the peak fluence $S_i$ and peak interval $\delta_i$ distributions within each burst are consistent with log-normal...

Source: http://arxiv.org/abs/astro-ph/9607131v1

4
4.0

Sep 18, 2013
09/13

by
Stirling A. Colgate; Hui Li

######
4

######
0

######
0

We propose that nearly every accelerated CR was part of the parallel current that maintains all force-free (f-f) magnetic fields. Charged particles are accelerated by the E-parallel (to the magnetic filed B) produced by reconnection. The inferred total energy in extra-galactic cosmic rays is 10^(60) ergs per galaxy spacing volume, provided that acceleration mechanisms assumed do not preferentially only accelerate ultra high energy cosmic rays (UHECRs). This total energy is about 10^5 times the...

Source: http://arxiv.org/abs/astro-ph/0509054v1

21
21

Sep 18, 2013
09/13

by
Hui Li; Edison P. Liang

######
21

######
0

######
0

We study quantitatively the formation and radiation acceleration of electron-positron pair plasmoids produced by photon-photon collisions near Galactic black holes (GBHs). The terminal ejecta velocity is found to be completely determined by the total disk luminosity, proton loading factor and disk size, with no dependence on the initial velocity. We discuss potential applications to the recently discovered Galactic superluminal sources GRS1915, GROJ1655 and possibly other GBHs.

Source: http://arxiv.org/abs/astro-ph/9509024v1

13
13

Sep 22, 2013
09/13

by
Stirling A. Colgate; Hui Li

######
13

######
0

######
0

Recent rotation measure observations of a dozen or so galaxy clusters have revealed a surprisingly large amount of magnetic fields, whose estimated energy and flux are, on average, $\sim 10^{58}$ ergs and $\sim 10^{41}$ G cm$^2$, respectively. These quantities are so much larger than any coherent sums of individual galaxies within the cluster that an efficient galactic dynamo is required. We associate these fields with single AGNs within the cluster and therefore with all galaxies during their...

Source: http://arxiv.org/abs/astro-ph/0001418v1

24
24

Jul 20, 2013
07/13

by
Jarrett L. Johnson; Hui Li

######
24

######
0

######
0

A rapidly growing body of observational results suggests that planet formation takes place preferentially at high metallicity. In the core accretion model of planet formation this is expected because heavy elements are needed to form the dust grains which settle into the midplane of the protoplanetary disk and coagulate to form the planetesimals from which planetary cores are assembled. As well, there is observational evidence that the lifetimes of circumstellar disks are shorter at lower...

Source: http://arxiv.org/abs/1203.4817v1

22
22

Sep 23, 2013
09/13

by
Jarrett L. Johnson; Hui Li

######
22

######
0

######
0

We estimate the maximum temperature at which planets can form via gravitational instability (GI) in the outskirts of early circumstellar disks. We show that due to the temperature floor set by the cosmic microwave background, there is a maximum distance from their host stars beyond which gas giants cannot form via GI, which decreases with their present-day age. Furthermore, we show that planet formation via GI is not possible at metallicities < 10^-4 Z_Sun, due to the reduced cooling...

Source: http://arxiv.org/abs/1212.1482v3

17
17

Sep 23, 2013
09/13

by
Feng Qi; Wen-Hui Li

######
17

######
0

######
0

In the paper, the authors first survey and review some logarithmically completely monotonic functions involving the gamma function and its various ratios, and then find sufficient conditions for a function involving the ratio of two gamma functions and originating from the coding gain to be logarithmically completely monotonic.

Source: http://arxiv.org/abs/1303.1877v1

11
11

Sep 22, 2013
09/13

by
Hui Li; F. D. M. Haldane

######
11

######
0

######
0

We study the "entanglement spectrum" (a presentation of the Schmidt decomposition analogous to a set of "energy levels") of a many-body state, and compare the Moore-Read model wavefunction for the $\nu$ = 5/2 fractional quantum Hall state with a generic 5/2 state obtained by finite-size diagonalization of the second-Landau-level-projected Coulomb interactions. Their spectra share a common "gapless" structure, related to conformal field theory. In the model state,...

Source: http://arxiv.org/abs/0805.0332v2

11
11

Sep 21, 2013
09/13

by
Wei Liu; Scott C. Hsu; Hui Li

######
11

######
0

######
0

We present results from three-dimensional ideal magnetohydrodynamic simulations of low $\beta$ compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are...

Source: http://arxiv.org/abs/0902.2485v2

9
9.0

Sep 20, 2013
09/13

by
Gabriel Rockefeller; Christopher L. Fryer; Hui Li

######
9

######
0

######
0

We present the results of 3-dimensional simulations of the direct collapse to a black hole of a rotating, 60-solar-mass, zero metallicity, population III star. Because the structure of this star (angular momentum, density and temperature profiles) is similar to many collapsar gamma-ray burst progenitors, these calculations have implications beyond the fate of population III stars. These simulations provide a first 3-dimensional look at a realistic collapsar progenitor, and the results are very...

Source: http://arxiv.org/abs/astro-ph/0608028v1

6
6.0

Sep 22, 2013
09/13

by
Yejun Zhou; Hui Li; Jianfeng Ma

######
6

######
0

######
0

In this paper, we propose an algorithm that targets contamination and eavesdropping adversaries. We consider the case when the number of independent packets available to the eavesdropper is less than the multicast capacity of the network. By means of our algorithm every node can verify the integrity of the received packets easily and an eavesdropper is unable to get any meaningful information about the source. We call it practical security if an eavesdropper is unable to get any meaningful...

Source: http://arxiv.org/abs/0805.2286v1

10
10.0

Jul 20, 2013
07/13

by
Masanori Nakamura; Hui Li; Shengtai Li

######
10

######
0

######
0

Stability properties of ``magnetic tower'' jets propagating in the gravitationally stratified background have been examined by performing three-dimensional magnetohydrodynamic simulations. The current-carrying, Poynting flux-dominated magnetic tower jet, which possesses a highly wound helical magnetic field, is subject to the current-driven instability (CDI). We find that, under general physical conditions including small perturbations in the initial background profiles, the propagating...

Source: http://arxiv.org/abs/astro-ph/0609007v1

13
13

Sep 23, 2013
09/13

by
Jingzhi Yan; Hui Li; Qingzhong Liu

######
13

######
0

######
0

We present the long-term optical spectroscopic observations on the Be/X-ray binary A0535+26 from 1992 to 2010. Combining with the public V-band photometric data, we find that each giant X-ray outburst occurred in a fading phase of the optical brightness. The anti-correlation between the optical brightness and the H$\alpha$ intensity during our 2009 observations indicates a mass ejection event had taken place before the 2009 giant X-ray outburst, which might cause the formation of a low-density...

Source: http://arxiv.org/abs/1111.0715v1

10
10.0

Sep 22, 2013
09/13

by
Jiangfeng Du; Hui Li; Chenyong Ju

######
10

######
0

######
0

We investigate quantum games in which the information is asymmetrically distributed among the players, and find the possibility of the quantum game outperforming its classical counterpart depends strongly on not only the entanglement, but also the informational asymmetry. What is more interesting, when the information distribution is asymmetric, the contradictive impact of the quantum entanglement on the profits is observed, which is not reported in quantum games of symmetric information.

Source: http://arxiv.org/abs/quant-ph/0308034v1

8
8.0

Sep 18, 2013
09/13

by
Shengtai Li; Hui Li; Renyue Cen

######
8

######
0

######
0

In this era of precision cosmology, a detailed physical understanding on the evolution of cosmic baryons is required. Cosmic magnetic fields, though still poorly understood, may represent an important component in the global cosmic energy flow that affects the baryon dynamics. We have developed an Eulerian-based cosmological magnetohydrodynamics code (CosmoMHD) with modern shock capturing schemes to study the formation and evolution of cosmic structures in the presence of magnetic fields. The...

Source: http://arxiv.org/abs/astro-ph/0611863v1

9
9.0

Sep 22, 2013
09/13

by
Hui Li; Masaaki Kusunose; Edison Liang

######
9

######
0

######
0

We consider stochastic particle acceleration in plasmas around stellar mass black holes to explain the emissions above 1 MeV from Galactic black hole candidates. We show that for certain parameter regimes, electrons can overcome Coulomb losses and be accelerated beyond the thermal distribution to form a new population, whose distribution is broad and usually not a power law; the peak energy of the distribution is determined by the balance between acceleration and cooling, with particles piling...

Source: http://arxiv.org/abs/astro-ph/9602028v1

5
5.0

Sep 23, 2013
09/13

by
Yuhua Sun; Tongjiang Yan; Hui Li

######
5

######
0

######
0

Cyclic codes are a subclass of linear codes and have important applications in data storage systems, and communication systems because of their e?cient encoding and decoding algorithms. Employing the First Class Whiteman's generalized cyclotomic sequences with order 4, we describe several cyclic codes over the ?nite ?eld GF(q) and give their generator polynomials. Additionally, Lower bounds on the minimum weight of these cyclic codes are presented.

Source: http://arxiv.org/abs/1303.6378v1

15
15

Sep 23, 2013
09/13

by
Hui Li; Hongsheng Zhang; Yi Zhang

######
15

######
0

######
0

We study the semi-holographic idea in context of decaying dark components. The energy flow between dark energy and the compensating dark matter is thermodynamically generalized to involve a particle number variable dark component with non-zero chemical potential. It's found that, unlike the original semi-holographic model, no cosmological constant is needed for a dynamical evolution of the universe. A transient phantom phase appears while a non-trivial dark energy-dark matter scaling solution...

Source: http://arxiv.org/abs/1212.2360v1

12
12

Sep 18, 2013
09/13

by
Hui Li; Jiangfeng Du; Serge Massar

######
12

######
0

######
0

We investigate the quantization of games in which the players can access to a continuous set of classical strategies, making use of continuous-variable quantum systems. For the particular case of the Cournot's Duopoly, we find that, even though the two players both act as "selfishly" in the quantum game as they do in the classical game, they are found to virtually cooperate due to the quantum entanglement between them. We also find that the original Einstein-Podolksy-Rosen state...

Source: http://arxiv.org/abs/quant-ph/0212122v2

8
8.0

Sep 19, 2013
09/13

by
Hui Li; Martin Olbermann; Donald Stanley

######
8

######
0

######
0

Let the circle act in a Hamiltonian fashion on a compact symplectic manifold $(M, \omega)$. Assume that the fixed point set $M^{S^1}$ has exactly two components, $X$ and $Y$, and that $\dim(X) + \dim(Y) +2 = \dim(M)$. We first show that $X$, $Y$ and $M$ are simply connected. Then we show that, under some minor dimension restrictions, up to $S^1$-equivariant diffeomorphism, there are finitely many such manifolds in each dimension. Moreover, we show that, up to non-equivariant diffeomorphism,...

Source: http://arxiv.org/abs/1010.2505v2

13
13

Sep 23, 2013
09/13

by
Alister W. Graham; I-hui Li

######
13

######
0

######
0

From a sample of 50 predominantly inactive galaxies with direct supermassive black hole mass measurements, it has recently been established that barred galaxies tend to reside rightward of the M_bh-sigma relation defined by non-barred galaxies. Either black holes in barred galaxies tend to be anaemic or the central velocity dispersions in these galaxies have a tendency to be elevated by the presence of the bar. The latter option is in accord with studies connecting larger velocity dispersions...

Source: http://arxiv.org/abs/0904.1290v2

5
5.0

Sep 21, 2013
09/13

by
Hui Li; Yang Chen; Li Zhang

######
5

######
0

######
0

G54.1+0.3 is a Crab-like pulsar wind nebula (PWN) with the highest $\gamma$-ray to X-ray luminosity ratio among all the nebulae driven by young rotation-powered pulsars. We model the spectral evolution of the PWN and find it difficult to match the observed multi-band data with leptons alone using reasonable model parameters. In lepton-hadron hybrid model instead, TeV photons come mainly from $\pi^0$ decay in proton-proton interaction and the observed photon spectrum can be well reproduced. The...

Source: http://arxiv.org/abs/1008.2704v1

10
10.0

Sep 20, 2013
09/13

by
Masanori Nakamura; Hui Li; Shengtai Li

######
10

######
0

######
0

Based on a new approach on modeling the magnetically dominated outflows from AGNs (Li et al. 2006), we study the propagation of magnetic tower jets in gravitationally stratified atmospheres (such as a galaxy cluster environment) in large scales ($>$ tens of kpc) by performing three-dimensional magnetohydrodynamic (MHD) simulations. We present the detailed analysis of the MHD waves, the cylindrical radial force balance, and the collimation of magnetic tower jets. As magnetic energy is...

Source: http://arxiv.org/abs/astro-ph/0608326v1

14
14

Sep 23, 2013
09/13

by
Yuhua Sun; Zilong Wang; Hui Li

######
14

######
0

######
0

Let $d=\frac{(3^{2k}+1)^{2}}{20}$, where $k$ is an odd integer. We show that the magnitude of the cross-correlation values of a ternary $m$-sequence $\{s_{t}\}$ of period $3^{4k}-1$ and its decimated sequence $\{s_{dt}\}$ is upper bounded by $5\sqrt{3^{n}}+1$, where $n=4k$.

Source: http://arxiv.org/abs/1105.2786v1

5
5.0

Sep 18, 2013
09/13

by
Lei Zhang; Hui Li; Dongning Guo

######
5

######
0

######
0

In many wireless communication systems, radios are subject to a duty cycle constraint, that is, a radio only actively transmits signals over a fraction of the time. For example, it is desirable to have a small duty cycle in some low power systems; a half-duplex radio cannot keep transmitting if it wishes to receive useful signals; and a cognitive radio needs to listen and detect primary users frequently. This work studies the capacity of scalar discrete-time Gaussian channels subject to duty...

Source: http://arxiv.org/abs/1209.4687v1

14
14

Sep 17, 2013
09/13

by
Jesse Pino; Hui Li; Swadesh Mahajan

######
14

######
0

######
0

The evolution equations for a plasma comprising multiple species of charged fluids with relativistic bulk and thermal motion are derived. It is shown that a minimal fluid coupling model allows a natural casting of the evolution equations in terms of generalized vorticity which treats the fluid motion and electromagnetic fields equally. Equilibria can be found using a variational principle based on minimizing the total enstrophy subject to energy and helicity constraints. A subset of these...

Source: http://arxiv.org/abs/0912.4543v2

7
7.0

Sep 18, 2013
09/13

by
Siming Liu; Christopher L. Fryer; Hui Li

######
7

######
0

######
0

Plasmas in an accretion flow are heated by MHD turbulence generated through the magneto-rotational instability. The viscous stress driving the accretion is intimately connected to the microscopic processes of turbulence dissipation. We show that, in a few well-observed black hole accretion systems, there is compelling observational evidence of efficient electron heating by turbulence or collective plasma effects in low accretion states, when Coulomb collisions are not efficient enough to...

Source: http://arxiv.org/abs/0705.0525v2

16
16

Sep 23, 2013
09/13

by
I-hui Li; Howard K. C. Yee

######
16

######
0

######
0

We present a structure finding algorithm designed to identify galaxy groups in photometric redshift data sets: the probability friends-of-friends (pFoF) algorithm. This algorithm is derived by combining the friends-of-friends algorithm in the transverse direction and the photometric redshift probability densities in the radial dimension. The innovative characteristic of our group-finding algorithm is the improvement of redshift estimation via the constraints given by the transversely connected...

Source: http://arxiv.org/abs/0801.2410v1

16
16

Sep 19, 2013
09/13

by
Hui Li; Dimitri Kusnezov; Francesco Iachello

######
16

######
0

######
0

We study the group theoretical properties of the Lame equation and its relation to su(1,1) and su(2). We compute the band structure, dispersion relation and transfer matrix and discuss the dynamical symmetry limits.

Source: http://arxiv.org/abs/solv-int/9912006v1

11
11

Sep 23, 2013
09/13

by
Hui Li; Siming Liu; Yang Chen

######
11

######
0

######
0

We show that the radio, X-ray and gamma-ray spectrum of the supernova remnant RX J1713.7-3946 can be accounted for with the simplest emission model, where all of these emissions are attributed to a population of relativistic electrons interacting with the cosmic microwave background radiation, IR interstellar photons, and a background magnetic field. With a spectral inversion method (Johns & Lin 1992), the parent electron distribution and its uncertainties are derived from the observed...

Source: http://arxiv.org/abs/1110.2857v1